Over the past few years, I've had the opportunity to work with the guys at Falafel Software. They recently decided to redo their company website, choosing Community Server as their blogging and forums engine.
I moved their existing blogs and comments from DNNForge into CS using hand-crafted SQL. The tricky part was turning their author-focused blogs into technology-focused blogs. Well, it wasn't that tricky. Just needed a couple of mapping tables.
They wanted to have a consistent set of menus across their site and CS let us do that easily. We gutted and replaced the contents of skin-repeaterbar.ascx in the {CS root}\Themes\Default\Skins folder.
Then Lino and Mike spent some time tweaking the stylesheets so that it would match the rest of the site. I think it turned out rather well.
UPDATE: Just wanted to make it clear that Lino designed the look and feel of the site. I'm artistically challenged. If somebody lays out what the skin should look like, I can make Community Server bend to their will.